JPS6330501A - Production of modified starch - Google Patents

Abstract

PURPOSE:To facilitate the formation of a modified starch which can give an adhesive, binder, sizing agent or coating agent excellent in both water and oil resistance, by reacting a starch with a modified dimethylpolysiloxane. CONSTITUTION:A starch (A) (e.g., potato starch) is reacted with 0.01-10 wt%, based on component A, modified dimethylpolysiloxane (B) of formula I [wherein X is an optionally substituted polyether group having an average MW of 1,000-100,000 and represented by formula II, R is a monovalent organic group, a + b > 14, a/a + b > 0.35, Y is (substituted) amino, -Cl or a group of formula III or IV, l is an integer, m is 0-20 and n is 1-20] suspended in water at 45 deg.C or below in the presence of a catalyst (C) selected from among a compound having a group of formula V (wherein X is O or S), e.g., (thio)urea, an amine (e.g., triethanolamine), a Lewis acid (e.g., stannic chloride), a tin or aluminum carboxylate (e.g., aluminium acetate).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing modified starch using modified dimethylpolysiloxane, and this modified starch is used as an adhesive having water resistance and oil resistance.

It can be used as a binder, sizing agent, coating agent, etc., and can also be used as a filler for polymers.

(Prior art) Methods for imparting water resistance to starch include etherification with epichlorohydrin, esterification with polymerized phosphate,
There is a method of crosslinking starch, such as by acetalization with aldehyde. Although these crosslinked starches have some degree of water resistance, they are not sufficient, they do not tend to become glue, making it difficult to use ordinary coating methods, and they also have the disadvantage of not having film-forming properties and not forming a film.

Further, since N-methylolpropionamide etherified starch (US Pat. No. 3,101,330) has an N-methylol group, it can be made three-dimensional by heating or an acid catalyst after coating to develop water resistance. However, during its production, the acid amide group is hydrolyzed and carboxyethylated products are produced, which impairs water resistance.
There is a problem in that the N-methylol groups condense and gel during the reaction.

Furthermore, methods for modifying starch using organosilane (JP-A-59-179501, JP-A-59-20790)
2) has also been proposed, but there is a problem that water resistance and oil resistance are weak because the silicon compounds are bonded by monomer units.

(Problems to be Solved by the Invention) As mentioned above, cross-linked starch with epichlorohydrin, polymerized phosphate, aldehyde, etc. does not have sufficient water resistance, and N-
Methylolpropionamide etherified starch has the problem that water resistance cannot be obtained unless it is made two-dimensional by heating or an acid catalyst, and water resistance and oil resistance are weak when using an organosilane method. Currently, there is no modified starch that has strong properties and is easy to produce and use.

(Means for solving the problem) As a result of intensive research to solve the above problem, we found that starch -
Obtained by reacting with modified dimethylpolysiloxane, which is a polymer of silicon compounds, using a compound having a C-N H2 (X = O or S) group, amines, Lewis acid, or a tin salt or aluminum salt of carboxylic acid as a catalyst. The modified starch was found to have strong water and oil resistance.

In the method for producing modified starch of the present invention, modified dimethylpolysiloxane is made repellent in water, starch is added to this suspension, the above-mentioned catalyst is then added, and the reaction is carried out with thorough stirring. However, the catalyst may be added before adding the starch. Although the reaction temperature may be room temperature, it is more advantageous to heat the reaction to a temperature below the gelatinization temperature of starch (generally about 40° C.).

When the reaction is carried out in a wet manner as described above, after the reaction, the modified starch of the present invention can be obtained by washing with water, dehydration, and drying by a known method.

It is also possible to heat starch to form a paste, add modified dimethylpolysiloxane and the above-mentioned catalyst, and react. The reaction temperature after gelatinizing the starch may be lower than the gelatinizing temperature of the starch.

The modified starch of the present invention obtained by the gelatinization reaction as described above can be used as it is, or can be dried by drum drying or the like and powdered.

In addition, by mixing modified dimethylpolysiloxane and the above-mentioned catalyst with starch at a moisture content of 2 to 50% using an appropriate mixing or kneading device, it is possible to work in a short time at a temperature higher than the gelatinization temperature of starch. It will also be possible to do so.

-C-NH2 (X=O or S) group is x
Examples of =O include urea, formamide, acrylamide and dimethylformamide. Examples of X=S include, for example, thiourea. These are used as 5-15% aqueous solutions or as solids or neat solutions. The amount added is 0.005 to 10% based on starch.

Amines include primary amines such as n-propylamine, tertiary amines such as diethylamine, tertiary amines such as trimethylamine, quaternary ammonium compounds such as tetramethylammonium hydroxide, diamines such as ethylenediamine, and triethanolamine. Unsaturated amines such as amino alcohols and allylamine can be used. these are,
It is used as a 5-15% aqueous solution or as a neat solution.

The amount added is 0.005 to 20% based on starch.

As the Lewis acid, stannous chloride, stannic chloride, ferric chloride, zinc chloride, etc. can be used.

These are used as solids or neat as 5-15% aqueous solutions. The amount added is o, o for W; J flour.
os ~ 10%.

As the tin salt of carboxylic acid, tin acetate, dibutyltin dilaurate, etc. can be used, and as the aluminum salt, aluminum acetate, etc. can be used. These are used as solids or neat as 5-15% aqueous solutions. The amount added is 0.005 to 10 per starch.
%.

Examples of starch raw materials that can be used to produce the modified starch of the present invention include wheat starch, potato starch, corn starch, corn starch, tapioca starch, sago starch, rice starch,
Unprocessed starch or wheat flour such as waxy corn starch, high amylose content corn starch, tapioca powder,
Also included are starch-containing materials such as corn flour and rice flour, and those obtained by etherification, crosslinking, oxidation, acid treatment, etc.

In the present invention, the modified dimethylpolysiloxane that can be used as a modifier has the following general formula % [In the formula, X is a group having an optionally substituted polyether moiety, and the molecular formula is 1082CH,O(C , H40) a
(C,HGO)bR (R is a monovalent organic group, a+b) 14
．． a/a+b>0.3j). Y is an optionally substituted amino group, or -C1, CH"CHx
m is an integer of O to 2o, n is an integer of 1 to 20, and the average molecular weight is 1,000 to 100,000. ] Also, the amount of modified dimethylpolysiloxane added is 0.01 to starch.
~10%.

(Function) The modified starch of the present invention exhibits hydrophobicity and lipophobicity only by the action of a very small amount of modified dimethylpolysiloxane.

When the modified starch of the present invention is coated and impregnated on paper or a board, the surface is covered with dimethylpolysiloxane bonded to the starch, resulting in water resistance and oil resistance. Additionally, as a secondary effect, the strength of the paper is improved.

The modified starch of the present invention using polyether-modified dimethylsiloxane has good dispersibility in water. but,
When it is applied to paper etc. in the form of a paste and dried after impregnation, the polyether part comes off and shows hydrophobicity and oleophobicity.On the other hand, the modified starch of the present invention using modified dimethylsiloxane without a polyether part , it remains thick in water without being wetted by the water, so it has poor dispersibility. It is necessary to use them properly depending on the purpose.

Although the modified starch paste of the present invention has a higher viscosity than its raw material starch, it does not adversely affect the dispersion of pigments and the like.

(Examples and effects of the invention) (Example 1) Epoxy-modified dimethylpolysiloxane (KF-102 manufactured by Shin-Etsu Chemical Co., Ltd., epoxy equivalent 4000) 0.
2 g was stirred and mixed into 260 g of water in a 40° C. water bath. After 15 minutes, 200 g of potato starch was stirred and mixed. 6.0 g of urea was made into an approximately 10% aqueous solution and mixed with stirring. The mixture was subsequently stirred for 4 hours. After that, the starch is filtered out,
Washed and dried.

The silicon content of the starch obtained by this method is 0°0333
%, and approximately 88% of the silicon provided by starch was fixed by starch.

A wet test of the modified starch was carried out by adding a small amount of starch to deionized water present in a beaker.

In this case, the total starch content remained suspended in water for at least 24 hours.

When the filter paper was soaked in a size solution with a concentration of 2% and dried, the filter paper exhibited hydrophobicity.

When the viscosity was measured at a concentration of 5%, it was 7600 cps (30'
C), and a significant increase in viscosity was observed compared to the raw material potato starch.

(Example 2) Epoxypolyether modified dimethylpolysiloxane (X
-22-3667 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.2 g was stirred and mixed in 260 g of water in a 40°C water bath. After 15 minutes, 200 g of potato starch was stirred and mixed. 6.0 g of formamide was mixed with stirring, followed by stirring for 4 hours. Thereafter, the starch was filtered off, washed and dried.

A wet test of the modified starch was carried out and when a small amount of starch was added to the ion exchanged water present in the beaker, the total starch amount immediately began to settle and when stirred it became a clean slurry.

After soaking the filter paper in a sizing solution with a concentration of 2%, when it was dried, the filter paper exhibited hydrophobicity as in Example 1.

(Example 3) Epoxy-modified dimethylpolysiloxane (molecular weight approximately 100
00) 0.2 g in 2 ml of water in a 40°C water bath
The mixture was stirred and mixed into 60 g of water. After 15 minutes, 200 g of corn starch was stirred and mixed. Thiourea 6.0g approximately 10%
This was made into an aqueous solution and mixed with stirring.The mixture was then stirred for 4 hours. Thereafter, the starch was filtered off, washed and dried.

Results similar to those of Example 1 were obtained in the wet test.

The filter paper that was dried after soaking in a size solution with a concentration of 2% was also used in Example 1.
As in the case of , it showed hydrophobicity.

(Example 4) 0.2 g of epoxy polyether modified dimethylpolysiloxane (molecular weight approximately 100,000) was stirred and mixed in 260 g of water in a water bath at 40°C. After 15 minutes, 200 g of tapioca oxidized starch was mixed with stirring. Stannic chloride 2.
6 g was made into an aqueous solution of about IQ% and mixed with stirring. The mixture was subsequently stirred for 4 hours. Thereafter, the starch was filtered off, washed and dried.

When the wet test was carried out, the starch immediately began to settle as in Example 2.

The filter paper that was dried after soaking in a size solution with a concentration of 2% was also used in Example 1.
(Example 5) Epoxy-modified dimethylpolysiloxane (molecular weight approximately 400
0) was stirred and mixed in 260 g of water in a 40°C water bath. After 15 minutes, 200 g of cationically modified starch was mixed with stirring. 15 g of triethanolamine was made into an approximately 10% aqueous solution and mixed with stirring. The mixture was subsequently stirred for 4 hours. Thereafter, the starch was filtered off, washed and dried.

A wet test gave similar results to Example 1.

The filter paper that was dried after soaking in a size solution with a concentration of 2% was also used in Example 1.
As in the case of , it showed hydrophobicity.

(Example 6) Epoxy-modified dimethylpolysiloxane (molecular weight approximately 110
000) I was dissolved in 30 m +2 n-hexane and mixed with 500 g of potato starch in a mixer, and 15 g of acrylamide dissolved in 50 m fl of water was added and mixed. This mixture was heated at 40-42°C for 4 hours. After cooling, it was poured into water, filtered, washed, and dried.

The same results as in Example 1 were obtained for both the wetness test and the hydrophobicity of the filter paper.

(Example 7) Epoxypolyether-modified dimethylpolysiloxane (molecular weight approximately 1,100,000) I was dissolved in 30 mR of n-hexane and mixed with 500 g of tapioca starch in a mixer, and 6.0 g of tin acetate was dissolved in 5On+0 water. Dissolved, added and mixed. This mixture was heated at 65-70°C for 2 hours. After cooling, it was poured into water, filtered, washed, and dried.

As in Example 2 in the wet test, the starch immediately began to settle.

The filter paper that was dried after soaking in a size solution with a concentration of 2% was also used in Example 1.
As in the case of , it showed hydrophobicity.

A filter paper impregnated with a size solution having a concentration of 2% was dried and subjected to the following tests.

1) When written with a glass marker pen (using Doolol as a solvent), the color does not bleed or transfer to the back of the paper.

2) When one drop of liquid paraffin is dropped onto a filter paper, the droplet remains as it is and does not soak into the paper.

(Example 8) Vinyl-modified dimethylpolysiloxane (molecular weight approximately 1000
0) 1 g was dissolved in 30 mQ of n-hexane and mixed with 500 g of corn starch in a mixer, and 4.1 g of aluminum acetate was dissolved in 50 mQ of water and mixed. This mixture was heated at 40-42°C for 4 hours. After cooling, it was poured into water, filtered, washed, and dried.

The same results as in Example 1 were obtained for both the wetness test and the hydrophobicity of filtration.

(Example 9) After 10 g of potato starch was gelatinized in 400 g of water at a temperature of 85° C. or higher, 0.1 g of epoxy-modified dimethylpolysiloxane (molecular weight about 4000) was added with stirring, and 3 g of dimethylformamide was added.

It was then cooled to room temperature. When the resulting solution was subjected to a filter paper test, it was found to be hydrophobic.

The entire solution was evaporated to dryness on a rotary evaporator. A 2% strength aqueous solution of the powder thus obtained again showed the same hydrophobicity.

(Example 10) After gelatinizing potato starch Log in 400 g of water at a temperature of 85°C or higher, 0.1 g of epoxy polyether modified dimethyl polysiloxane (molecular weight approximately 10,000) was added with stirring, and 6 g of trimethylamine was added. Ta. It was then cooled to room temperature.

In the filter paper test, the filter paper showed hydrophobicity both after impregnation with a modified starch solution and after impregnation with a solution of powder that had been evaporated to dryness.

(Comparative Example 1) Epoxy-modified dimethylpolysiloxane (K F-10
2) 0.2g was mixed with 200g potato starch. When a wet test was performed on this mixture, the starch immediately began to settle.

Also, after soaking the filter paper in this paste solution with a concentration of 2%.

Even when dried, the filter paper did not exhibit hydrophobicity.

(Comparative Example 2) Epoxypolyether modified dimethylpolysiloxane (X
-22-3667) was mixed with 200 g of potato starch.

Even when the filter paper was soaked in a size solution of this mixture having a concentration of 2% and then dried, the filter paper did not exhibit hydrophobicity.

Claims (4)

[Claims] (1) Starch ▲There are mathematical formulas, chemical formulas, tables, etc.▼, (X
1. A method for producing modified starch, which comprises reacting with modified dimethylpolysiloxane using a compound having a =O or S) group, amines, a Lewis acid, or a tin or aluminum salt of a carboxylic acid as a catalyst. (2) The modified dimethylpolysiloxane is suspended in water, starch is added to this suspension, the catalyst is then added, and the resulting suspension is stirred at a temperature of up to 45°C. The method described in scope item (1). (3) The method according to claim (1), wherein starch and water are heated to form a size liquid, and modified dimethylpolysiloxane and a catalyst are added to this size liquid. (4) The method according to claim (1), wherein the modified dimethylpolysiloxane and catalyst are mixed with starch at a moisture content of 2 to 50% using a mixing or kneading device.